The "Small" Models
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J.F. Francois, Tinbergen Institute and CEPR |
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© J.F. Francois, 1998-2003 |
These
examples involve a GAMS/MPSGE multi-region general equilibrium model. The set
of files (found in the subdirectory "small" on the CD-ROM in the
"course" directory, and installed under the "course"
directory on the C: drive if the course material has been installed from the
CD-ROM) provides a GAMS-based version of two standard styles of multiregion CGE
models:
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(1)The GTAP model |
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(2) Robinson-deMelo syle models. |
Both
models are distributed with the same region and sector structure as in the
GEMPACK-based SIMPLE model. The dataset is based on the GTAP dataset version 3,
aggregated as follows:
Model Regions and
Sectors
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regions |
sectors |
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Japan Rest of World |
primary production manufactures services |
Viewing
social accounting data: Note that the model data (including a file in SAM
format) can be viewed in the SIMPLE directory with the utility
"Viewhar", reachable from the WinGEM menu under HA Files. (See the
notes on the SIMPLE model.) Alternatively, you can look at the social
accounting data in the GAMS data input files (see below), which are simple text
files.
The basic
social accounting data for Japan are summarized in the following table:
The Models
(1) mtrmge.gms: This
model is essentially identical to the GTAP model, with the exception of
consumer preferences, which are Cobb-Douglas over consumer goods in this
example (instead of CDE as in the GTAP model).
Trade is Armington based, and involves transport services. Consumption,
Investment, and Government take fixed shares of income.
This is an MPSGE model, based primarily on Tom Rutherford's GTAP data-based CGE
model and the WTO's MPSGE-based model (written by Francois, McDonald, and
Nordstrom.)
The experiments can be executed from batch files from within the Windows
Explorer menu (or alternatively from within a DOS box). There are three
experiment files for this model:
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EXP1.BAT |
a move to global free trade |
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EXP2.BAT |
a change in domestic output taxes |
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EXP3.BAT |
a change in consumption taxes |
(2)
mrtmge1.gms: This is a deMelo-Robinson style CGE model. There is
a CET transform technology between exports and domestic goods. Also, government
and investment demand are fixed.
The experiment here involves:
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EXP4.BAT |
a move to global free trade |
(3)
running the models: You can either run the models from the DOS prompt:
typing (for experiment 1)
GAMS
EXP1
or you can also
execute the models from the Windows Explorer menu.
Note: The most recent version of GAMS comes with a graphical
interface: GAMSIDE. However, this is not available for student applications.
The initial experiment batch file initiates a sequence of file calls, as
detailed in the figure below.
The
models require GAMS, with an installed MCP solver (MILES or PATH). A
student/demonstration version is distributed on the course CD. This is
sufficient to run the models. However, larger models will require a full GAMS
license. The student/demonstration version is distributed with permission.
The
student version of GAMS requires 19.9 Mb of free disk space. The model
directory requires 85.1 Kb of free disk space. The version of GAMS distributed
with the course disk is for a DOS/WIN95/WIN98/WINNT environment. (It may work
with WIN2000. I just don't know.)
Once you
have run the model, you can view the resuls of Experiment % by using the text
editor to view file EXP%TABS.TXT. Examples are presented below: Longer output
files are contained in the list file EXP%.LST.
Note: The most recent version of GAMS comes with a graphical interface:
GAMSIDE. However, this is not available for student applications.
Technical notes and documentation
The aggregation of this model is based on a 2 region, 3 sector version of the
GTAP dataset. Much larger aggregations are possible, and many additional
aggregations are available from the GTAP consortium from its web site at:
http://www.agecon.purdue.edu/gtap.
You will need to employ a version of Rutherford's GTAPinGAMS utilities to move
the GTAP data (which are GEMPACK based) to a GAMS.
You can
download GAMS code for GAMS/MPSGE conversions of GTAP from Rutherford's web
page:
http://nash.colorado.edu/tomruth/gtapingams/html/gtapgams.html
Supporting
documentation for the theory of the GTAP model is available from the following
source:
[1] Hertel, T.W.
and Tsigas, M. (1996) "The Structure of GTAP," in T.W. Hertel, ed., Global Trade Analysis, Cambridge
University Press, Chapter 2.
Thomas
Rutherford's interpretation of GTAP within GAMS/MPSGE is explained in this
document:
[2] T. Rutherford
(1998). "GTAPinGAMS: The Dataset and Static Model." University of
Colorado, September.
More
generically, modelling in GAMS/MPSGE is explained in the following:
[3] T. Rutherford
(1998). "Economic Equilibirum Modelling with GAMS: An Introduction to
GAMS/MCP and GAMS/MPSGE" University of Colorado, June.
Note: The models distributed here do not follow Rutheford's representation
of GTAP. Rutherford employs a hybrid model, with deMelo-Robinson type
macroeconomic closure rules and CET transfromations betwee exports and domestic
goods. The models distributed in this package distinguish between a more or
less classic GTAP approach, and that of deMelo and Robinson.
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SMALL DIRECTORY FILES |
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EXP#.gms |
the experiment # itself |
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gams2tbl.gms |
a routine to write results as tables |
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gams2tbr.gms |
a smaller version of gams2tbr.gms (to facilitate running within the student license.) |
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gtap4001.set |
set mapping information |
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mrtdata.gms |
gamscode to process the model data |
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mrtmge.gms |
a version of the GTAP model itself |
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mrtmge1.gms |
a deMelo-Robinson-style model |
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small.gms |
the model data |
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small.map |
set definition file |
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small.par |
paramater file |
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small.set |
dataset definition file |
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readme.txt |
a text-based file with instructions for working in a DOS environment |
NOTE:
Output files will have *.lst names. There will also be summary table files with
*.txt extensions. You may want to focus on the *.txt files when comparing
results.